https://bugs.openldap.org/show_bug.cgi?id=8174
--- Comment #4 from Vladimir Cunat vladimir.cunat@nic.cz --- FYI, blocking the transaction after mdb_drop isn't great. Some projects got caught by that: postfix, knot-dns, knot-resolver (I didn't search specifically, so maybe more).
Personally I find it useful to clear the whole DB and fill new contents, all within a single RW transaction (so that noone sees the WIP state during that rewrite). But I guess everyone will have to try to find some workarounds now...